1. Field of the Invention
The present invention relates to a linear motor, and more particularly to a linear motor capable of effectively cooling heat generated when the linear motor is driven.
2. Prior Art
As shown in FIG. 1, a moving magnet type of linear motor 101, having two movable tables, is equipped with long plate-shaped stator base 102. Linear guide projection 103 is formed into a single structure to compose a linear guide by protruding to the outside on the lateral surface of this stator base 102. A printed circuit board, not shown, is arranged on the upper surface of stator base 102, and stator armature 107 is formed by adjacently arranging armature coils 104 in close contact so as not to overlap on top of the printed circuit board. Armature coil 104 is formed by winding a large number of turns of a conductor. Each armature coil 104 is arranged adjacent to another armature coil 104.
Each armature coil is formed by winding so that a single magnetic pole of field magnets 105 and 106 is taken to be the space T. Conducting portions 104c and 104d are portions that do not contribute to generation of thrust.
A first position detection device group 108 and a second position detection device group 109 are arranged on stator armature 107. Hall effect ICs, Hall elements, and electromagnetic conversion devices such as electromagnetic resistors can be used for position detection devices 108 and 109. Reference numerals 104a and 104b denote conducting portions, respectively.
Field magnets 105 and 106 have a horizontal width that is equal to the horizontal width of armature coil 104. As a result, since both first and second position detection device groups 108 and 109 will end up detecting the magnetic poles of first and second field magnets 105 and 106, unless some action is taken to prevent this, first and second moving elements 110 and 111 end up moving on their own. In order to prevent this, field magnet 105 is arranged on the main body (not shown) of first moving element 110 shifted by a prescribed width (width of conducting portion 104d of armature coil 104) in the direction of the lateral surface of one of stator armatures 107. The above-mentioned constitution is such that first position detection device group 108 and second position detection device group 109 are arranged by shifting by a prescribed width, in advance, so that first moving element 110 and second moving element 111 are not detected simultaneously. Further, with an absence of a cooling system, a load due to overheating of the stator and moving elements occurs when the motor is used for a long time period.
An object of the present invention is to provide a linear motor capable of accurately maintaining motor characteristics through an effective cooling of the moving element and the stator element of the linear motor.